1. The Hypochlorite of Alkaline Metal.
Hypochlorite of alkaline metal and, particularly, the sodium hypochlorite (NaOCl), has been used since the 19th century for its antiseptic properties. Alkaline metal hypochlorite is an alkaline metal salt of hypochlorous acid. The available chloride level of sodium hypochlorite solutions is equal to the addition of HOCl (hypochlorous acid) and OCl− (hypochlorous anion) concentrations (Bloomfield & Miles, 1979). The hypochlorite active form, i.e., the hypochlorous acid, is a highly strong oxidant that plays a role in the mammalian defense system. HOCl is synthesized in polymorphonuclear neutrophils and monocytes (Wright et al., 1986) during the respiratory burst by the myeloperoxidase-H2O2-halide system. Hypochlorous acid is unstable and reacts readily with primary and secondary amines to generate various N-chloramines (Zgliczynski et al., 1971).
In polymorphonuclear cytosol and, especially in neutrophil cytosol, an amino acid (i.e. taurine) is particularly abundant and has a very high reactivity with hypochlorous acid to yield the taurine N-chloramine (TauCl). This chloramine is less toxic and reactive than hypochlorous acid. In addition, TauCl is the most stable of the chloramines (Zgliczynski et al., 1971; Marquez & Dunford, 1994). Moreover, taurine seems to have a high protective role in both intra- and extra-cellular environments, via its high scavenger activity with hypochlorous acid (Cantin, 1994; J. Marcinkiewicz et al., 1998). However, long-lived taurine N-chloramines can move and react (i.e., oxidize and/or chlorinate) at distance from their formation to generate tissue damage (Zgliczynski et al., 1971).
At the physiological pH (7.4), taurine and hypochlorous acid react spontaneously and with a 1/1-molecule stoechimetry to yield a taurine N-monochloramine. At acidic pH, this reaction generates both taurine N-monochloramines and taurine (N,N)-dichloramines. Taurine and, particularly, nitrites (NO2−), compete with other antioxidants to scavenge hypochlorous acid in the extracellular medium. Their concentrations are roughly equal. Thus, the main hypochlorous acid scavengers are nitrites, which react together to yield a lesser toxic derivative than TauCl. In the polymorphonuclear neutrophil cytosol, due to its high concentration (≈20 mM), taurine is the main scavenger of hypochlorous acid (J. Marcinkiewicz, 2000).
2. Sodium Hypochlorite, Hypochlorous Acid, N-Chloramine Properties.
a. Dissolving Tissue Abilities.
In aqueous solution, the sodium hypochlorite (NaOCl) is well known to be caustic. It is a non-specific agent able to hydrolyze necrotic tissues. This property is due to the presence of sodium hydroxide (NaOH). The tissue dissolving level (e.g. mainly necrotic tissues) is in accordance with NaOCl concentration, contact surface (Hand et al., 1978), contact time and NaOCl solution amount used (The et al., 1979).
Thus, even if a NaOCl concentration lower than 0.5% is not good enough to totally dissolve necrotic tissues, the reduced toxicity of these low concentrations is interesting. However, this decreased ability to dissolve necrotic tissues may be made up for by a NaOCl temperature increased to 37° C., even if at this temperature, the NaOCl stability is below 24 hours.
b. HOCl and Taurine N-monochloramine Stability in Aqueous Solution.
Sodium Hypochlorite (NaOCl):
Sodium hypochlorite is a highly unstable molecule. At levels below 5 g/l of available chlorine, its stability is under 2 weeks and depends on the following factors:                Light: Sodium hypochlorite is highly sensitive to light and should be protected by suitable packaging.        Temperature: NaOCl is highly sensitive to temperature greater than 30° C.        Presence of metal or organic matter: hypochlorite aqueous solution (containing HOCl molecules) (i.e.: NaOCl+H2OHOCl+NaOH) is neutralized by organic matter. Hypochlorite solution is efficient both when it can act readily and when it is in excess in comparison to an organic matter amount.        pH value: EP 0471129 A1 has established that a pH value between 10 and 10.5 yields a high stability to NaOCl oxidative activity (greater than 24 months).Taurine N-chloramine:        
At a physiological pH (7.4) and at 37° C., the taurine N-chloramine is the more stable of the chloramines (the oxidative activity decrease is below 5%/hour at 37° C.) (Grisham M B, Jefferson M M, Melton D F, Thomas E L—J. Biol. Chem. 1984; 259: 10404-13). However, in aqueous solution, the solubility of taurine N-chloramine sodium salt with a pH value between 7 and 8 is greater, but has a lower stability of its oxidative activities (DE 4041703 A1), and at a pH=8.3, the stability decreases by around 30% in 15 days followed by a decrease of around 0.71% per day (i.e. this equals a decrease of around 61% in 65 days).
c. Cell Toxicity and Viability.
Cell toxicity results mainly from an intracellular protein loss, which generates both an adherence decrease to substrates and cell deformation.
Cell viability alteration results mainly from the irreversible decrease of mitochondrial activity and therefore, a reduction of energy generated by cell respiratory.
The vulnerability of different cell organisms to NaOCl and TauCl depends on many factors:                The exposition level of the cell surface. Thus, cell systems with a high cell organization e.g. in epithelium and dental plaque are less sensitive (i.e. surface cells are sacrificed for profound cells) than one-cell systems (prokaryotes, mammalian mobile cells, or other one-cell systems).        Membrane type that protects intracellular elements (i.e. membrane permeability level to oxidants). The most efficient are viral proteinic membranes.        A membrane presence that protects key intracellular systems (e.g., DNA (nucleus), energetic production (mitochondria), secretion process (Golgi's apparatus), etc.). Prokaryotes do not possess these protector systems and, consequently, are more vulnerable.        The intracellular antioxidant amount (i.e., gluthatione, acetyl N-cysteine, taurine, amino acids, thiol groups, etc.) that is specific for each cell type. Prokaryotes possess a down antioxidant level.        The extracellular antioxidant amount (i.e. taurine, thiol groups, organic matter, metal, blood, extracellular matrix, etc.).        The liquid flux level that irrigates cells and, consequently, dilutes oxidants.        The exposition time to oxidants.        The local physicochemical environment (e.g. surface-active, oxidants, olfactory or gustatory properties, pH, pKa, density, solubility, viscosity, coloration, water-ectanol sharing factor).        
In a therapeutic treatment in vivo, the factors described above should be integrated for the determination of active agent levels to adapt them to both clinic status and therapeutic aims.
i) Sodium Hypochlorite (NaOCl) or Hypochlorous Acid (HOCl):
On the rat macrophage like-cells RAW 264.7, with a (NaOCl)=1 mM (NaOCl concentration), the cell viability is highly altered (irreversible) (Park E. et al., 1997).
On the mouse macrophages, with (HOCl)>0.125 mM, cell death increases significantly. This toxicity is abolished by a nitrite (NO2−) excess (NO2− alone does not generate cytotoxic activity) (Marcinkiewicz J. et al., 2000).
On human macrophages, fibroblasts and keratinocytes, in vitro:                With (NaOCl)=13.433 mM, toxicity is so great that it cannot be neutralized by antioxidants (i.e. with physiological concentrations).        With (NaOCl)>6.7165 mM, NaOCl has a high toxicity.        With (NaOCl)<3.358 mM, toxicity can be neutralized by an antioxidant addition.        With (NaOCl)<1.679 mM, toxicity is very low with an antioxidant presence (Hidalgo E. & Dominguez C., 2000).        The adherence loss of macrophages generated by HOCl: With (NaOCl)=1.0075 mM, after two hours of contact in vitro, 95% of the cells are alive but only 40% keep their adherence to substrates.        
On human endothelial cells in vitro (Pullar J M et al., 1999):                With [HOCl]≦25 μM, HOCl is not toxic.        With [HOCl]>25 μM, cell toxicity increases progressively (exposition time-dependent).        With [HOCl]=50 μM, some cell contractions were observed, the cells became rounded within the first 10 minutes and some lost their adherence after one hour and the majority after three hours.        
On human fibroblasts in vitro:                With (NaOCl)≧1.0075 mM (observed for 24 hours after a 15-minute exposition) cell viability is altered.        With (NaOCl)=16.791 mmol/l cell morbidity is complete.        For 67.165 μmol/l<(NaOCl)<671.655 μmol/l, 100% of cells are alive.        With (NaOCl)<671.655 μmol/l, and a FCS presence (2%), cell viability is not altered (24 hours of exposure) and both growth and cell proliferation are stimulated (the latter enhance with the (NaOCl) decrease and with a highest efficiency at 33.582 μmol/l) (Hidalgo E. & Dominguez C., Life Sci. 2000 Aug. 4; 67(11):1331-44).        With (HOCl)<50 μM, HOCl does not alter in vitro human fibroblast skin viability and does not induce cell apoptose (Vile G. F. et al., 2000).ii) the Effects of Taurine N-chloramine (TauCl) on Cell Viability:        
On rat C6 glioma cells, a (TauCl)=0˜2 mM does not alter cell viability in vitro (Liu Y. et al., 1999).
On human skin fibroblasts, a (TauCl)≦100 μM does not induce cytotoxicity or cell apoptose in vitro (Vile G. F. et al., 2000).
On human synoviocytes-like fibroblastes, with (TauCl)=400-500 μM, cell morphology changes (˜30%-50% of cells took a rounded form and lost their adherence to the plastic surfaces) although viability has been preserved (≧95%) (Kontny E. et al., 1999).
On mouse T cells:                With (TauCl)=30-300 μM, cell viability is not altered (i.e. mitochondrial activity).        At 300 μM, TauCl is cytotoxic (Marcinkiewicz J. et al., 1998).        
On mouse dendritic cells incubated 24 hours with TauCl:                For 0.05 mM<(TauCl)<0.5 mM, mitochondrial activity (cell viability) is not altered.        With (TauCl)>0.5 mM, cell viability decrease significantly (Marcinkiewicz J. et al., 1999).        
On macrophages or macrophage-line cells, with a (TauCl)=50˜600 μM, cell viability is not altered. (TauCl)>1 mM alters it (Marcinkiewicz J. et al., 1995).
d. Cellular Take-up of Exogenous HOCl and Taurine N-chloramine.
HOCl is a lipophilic oxidant and, consequently, easily and readily cross cell membranes (i.e. ˜80% of HOCl molecules are taken up by human fibroblasts within the first 10 minutes) (Vile G. F. et al., 2000). In vitro with (HOCl)=35 μM, endothelial cells take up 50% of HOCl molecules within ½ minute and 100% within 15 minutes, with a high majority within the first 10 minutes (Pullar J. M. et al., Am J Physiol. 1999 October; 277(4 Pt 2): H1505-12).
TauCl is taken up by specific transport systems. Therefore, in vitro, the Km and the Vmax values in relaxed rat RAW264.7 cells are 23.3 μM and 51.3 pmol/min/106 cells, respectively (Km=28.1 μM and Vmax=90.9 pmol/min/106 cells for taurine).
In LPS-stimulated macrophages, Km=45.9 μM and Vmax=82.6 pmol/min/106 cells for TauCl, and Km=17.3 μM and Vmax=116.3 pmol/min/106 cells for taurine.
Membrane transport systems are specific to each of these molecules and depend on Na+ level, temperature, and energy.
The blood biodistribution of TauCl and taurine induce a ready take up by cells of liver, lung, spleen, stomach, intestine and kidneys. In addition, cells present within an inflammatory site readily take up these two molecules (with a inflammation/blood ratio equal to 6.43 and 4.84 respectively) (Kim C. et al., 1998). Others data show a ready take up by kidneys, liver, spleen, and marrow. The take up by heart and muscle is slow (Huxtable R J, J. Nutr. 1981; 111:1275-86).
e. Antiseptic Properties.
Sodium hypochlorite is a very strong and efficient bactericidal, virucidal and fungicidal agent (Shih et al., 1970; Bloomfield & Miles, 1979, Harrison & Hand, 1980). The bactericidal minimum concentration of NaOCl (i.e. for Gram− and Gram+ bacteria) is 3.36 mM (0.025%) (Heggers J. P. et al., 1991) and the minimum virucidal concentration for VIH is 19.062 mM (1%) of available chlorine.
In contrast, TauCl has a very low bactericidal activity. Only dichloramines generate some bactericidal activity (i.e. with E. Coli in acidic conditions) (Marcinkiewicz J. et al., 2000).
3. Inflammation.
Inflammation is a defense mechanism toward all aggression types. Sentinel cells (e.g. macrophages and dendritic cells (DC)), that generate an immune system initialization via both a generation and a release of mediators detect an aggressor (Marcinkiewicz J. et al., 1999). These mediators induce a reaction cascade and both activate and regulate the immune system in an adaptive manner to the aggression type. After the aggressor agents are removed, a regulatory system generates an inflammation turnover followed by a healing/regeneration process.
Two immunity types are perceived: innate (natural) and acquired (adaptive).
The cell part of the innate (natural) immunity is made up of monocytes (mononuclear phagocytes), polymorphonuclear neutrophils (PMN), and natural killer cells (NK). These cells use the complement cascade, or some recognition protein, e.g., reactive protein C and amyloid protein. These proteins are able to attach themselves to carbohydrate molecules present on bacteria membranes. PMNs are included in the first mammalian defense line and cooperate closely with macrophages (one of the major effector cells of the immune system). PMNs are responsible for the non-specific defense in acute inflammation and macrophages take a similar role in both acute and chronic inflammations (Marcinkiewicz J. et al., 1994).
The acquired (adaptive) immunity involves several T cell types and uses antibodies as effector proteins. T cell receptors and antibodies are recognition molecules. B cells recognize carbohydrates, proteins, and some simple chemical structures while T cells recognize only peptides.
Dendritic cells (DC) play an important role. Under inflammatory mediator action, DCs migrate from non-lymphoid tissues to lymphoid organs where they lose their ability to scavenge antigens and acquire an increasing ability to stimulate T cells (Marcinkiewicz J. et al., 1994).
4. Inflammatory Mediators.
Cytokines are the most important intercellular messenger molecules of the immune system (Megarbane B. et al., 1998). Cytokines are generated and released from activated immune cells and they induce some particular biological activities after binding to a specific target cell receptor, in an autocrine or a paracrine manner. Macrophages and T cells are main productive cells of cytokines, although many other cells also can produce them. Cytokines are main and real regulators of both humoral and cellular immune response. Cytokines travel together and the balance of their activities is crucial for immune system regulation, e.g., via a competition between TH1 (IL-2, INF-γ, TNF-β and IL-12) and TH2 (IL-4, IL-5, IL-10 and IL-13) T cells.
TH1 cells are involved in cell immunity and are responsible for cytotoxic activities of macrophage, T cells and natural killer cells.
TH2 cells are associated with humoral response, and, for example, IL-10 (i.e. a TH2 type cytokine) strongly inhibits effective functions of macrophages and TH1 cells (Marcinkiewicz J., 1997).
Cytokine regulatory functions can be extended to a selection of immunoglobulin isotypes during humoral response. Thus, selective inhibitions of cytokines generate an immune response modulation.
Eicosanoids (prostaglandins and leukotrienes) and nitric oxide (NO), produced by activated macrophages, have an important role in the regulation of cytokine production. Eicosanoids are generated from arachidonic acid, which is derived from cell membrane phospholipides.
Prostaglandines (PG) are generated under the cyclooxygenase (COX) catalyzing action. Two cyclooxygenase types are distinguished: the constitutive form (COX1) and the induced form (COX2). COX2 production is activated within inflammatory cells by pro-inflammatory mediators. Thus, COX2 catalyzes the synthesis of prostaglandins E2 (PGE2) and prostacyclins I2 (PGI2) in macrophages, and prostaglandines D2 in mast cells.
Prostaglandins (particularly PGE2) and leukotrienes (particularly LTB4) change immune responses. Therefore, equilibrium in both production and effects of these eicosanoids is needed to induce a harmonious functioning of the immune system.
Nitric oxide (NO) is synthesized from L-arginine under the catalyzing action of the constitutive nitric oxide synthetase ((cNOS) that is calcium dependent) or the induced nitric oxide synthetase ((iNOS) that is calcium independent).
cNOS permits the synthesis of the basic form of nitric oxide (NO) in cells of both endothelium and nervous system.
iNOS is found in a variety of cells including macrophages, neutrophils and hepatocytes. NO generation plays an important role in macrophage cytotoxicity and their ability to kill pathogen microorganisms and, consequently, in mammalian non-specific defense against many pathogens and tumor cells.
More characteristics of these inflammatory mediators are described in Knight J A et al., 2000; Marcinkiewicz J. et al., 1997; and Megarbane B et al., 1998.
5. The Influence of Hypochlorous Acid and Taurine N-chloramine on an Inflammatory Site.
On Bacteria.
Rat peritoneal macrophages stimulated by non-chlorinated Gram+bacteria (Staphylococcus aureus, S. epidermidis, and Escherichia coli) release high concentrations of nitric oxide, TNF-α, and IL-6. The same bacteria chlorinated by HOCl lose their abilities to induce a nitric oxide and TNF-α release while IL-6 production and phagocytosis are not altered (Marcinkiewicz J. et al., 1994).
On Endothelium.
HOCl increases the endothelium permeability and promote leukocyte adherence to microcirculation endothelium. Taurine N-chloramine reduces an endothelium permeability increase generated by PMN activities. Taurine alone is without effect (Tatsumi & Flies, 1994).
On Cellular Growth.
In vitro, on endothelial cells of the human umbilical vein, a HOCl down level (5 nM/1.2×105 cells) does not induce a cell death but a temporary stop of cell growth (Vissers M C et al., 1999). In addition, low concentrations of both HOCl and physiological chloramines lead in vitro to an inhibition of DNA synthesis and cell division on skin fibroblasts (Vile G F et al., 2000).
On Non-free Proteins (e.g. Collagen, etc.).
HOCl is a very strong oxidant. In addition, HOCl chlorinates proteins and makes them more vulnerable to an endopeptidase-degradation. Thus, HOCl contributes to a destruction of the tissue surrounding the inflammatory site. TauCl is an oxidant with lower strength and seems to have a lesser responsibility for damage to these tissues.
On Collagenases.
TauCl induces a direct inhibition/inactivation of collagenases while it has no effect on the collagen proteolytic susceptibility. In comparison, leucine and alanine N-monochloramines have no inhibitory effect on collagenases and increase the proteolytic susceptibility of collagen (Davies J M S et al., 1994).
On Free Proteins (Ovalbumin, Bacterial Enzymes, etc.).
Free protein chlorination enhances their immune sensitivity, likely via an improvement of both their treatment and presentation by antigen-presenting cells (i.e. macrophages and dendritic cells). This chlorination is ten times more important for HOCl than taurine-N-monochloramines (TauCl) but, in vivo, TauCl is more stable and, consequently, TauCl can be regarded as the main physiological chlorinating agent (Marcinkiewicz J. et al., 1999).
On Dendritic Cells (DC) (Marcinkiewicz J. et al., 1999).
Two hours pre-incubated rat DCs with TauCl underwent a concentration-dependent inhibitory activity. Thus, a TauCl concentration equal to 500 μM ((TauCl)=500 μM) almost completely inhibits the DC release of reactive oxygen agents (ROS) generated via a respiratory burst, nitric oxide, PGE2, TNF-α, IL-6, IL-10, and IL-12. In addition, the lipopolyssacharide-induced expression of MHC type II and molecule B7-2 is also inhibited. At this concentration, TauCl may be toxic to DC when they are exposed for a long time. With (TauCl)=250 μM, TauCl has a more selective action. Therefore, it inhibits the production of IL-10, IL-12, PGE2, and nitric oxide. TNF-α and ROS generation is not inhibited. In addition, a DC exposition to TauCl seems to promote a TH1 response and decreases the TH2 activity.
On T Cells.
TauCl inhibits the release of IL-2 and IL-6 by T cells pre-incubated with a (TauCl)=100-300 μM and stimulated with either a mitogen, an antigen or an ovalbumin-APC complex (Marcinkiewicz J. et al., 1998).
On Phagocytes.
Antigens chlorinated by HOCl or TauCl do not induce an production of inflammatory mediators by the phagocytes that phagocytosed these antigens (Marcinkiewicz J. et al., 1994 & 1997).
On Macrophages.
Chloramines such as taurine N-mono and (N,N)-dichloramine, N-monochloro-ethanolamine and N-dichlorophosphoethanolamine as well as NaOCl (sodium hypochlorite), all inhibited the release of nitric oxide in a dose-dependent manner. Serine N-chloramine (SerCl) had a lesser half-life than TauCl (immediately after its preparation, (SerCl)=300 μM inhibited the nitric oxide generation for 85%; after 24 hours, this inhibition was reduced to 22%). TauCl inhibited the oxide nitric generation for 98% with (TauCl)=600 μM and 8-22% with (TauCl)=100 μM (i.e., this value changes with cell type). This inhibitory effect was executed within the iNOS gene transcription. Taurine alone was without effect (Marcinkiewicz J. et al., 1995). HOCl (likely via TauCl activity) and TauCl inhibited COX2 post-transcriptional expression i.e. four-hours delay on the kinetic expression of mRNA (and consequently the PGE2 production) and TNF-α transcriptional velocity (i.e., in a dose-dependent manner with an IC50=400 μM) (Quinn M R et al., 1996). TauCl inhibits COX2 expression either in non-stimulated and INF-γ-stimulated macrophages. In contrast, in INF-γ-stimulated macrophages TauCl inhibits both the iNOS expression and the production of TNF-α and IL-6. TauCl had no effect on IL-1α production for all stimulation levels. The native taurine alone had no effect on cytokine production. In addition, HOCl-oxidized plasma lipoproteins had an ability to reduce iNOS mRNA synthesis and, thus, to inhibit the nitric oxide production and contribute to atherosclerotic lesion development (Moeslinger T et al., 2000).
On Polymorphonuclear Neutrophils.
TauCl inhibits production of nitric oxide, PGE2, IL-6 and TNF-α in a dose-dependent manner. Native taurine has no effect. Some experiments (Marcinkiewicz J et al., 1998 & 2000) with luminol chemiluminescence-dependent (LCL) measures have shown the following:                Both taurine and TauCl reduced ROS production. However, only high taurine concentrations altered LCL and taurine activity is lower than TauCl.        HOCl reduces myeloperoxidase activity in a retroactive dose-dependent manner. In vitro, TauCl and HOCl inhibit myeloperoxidase extracted from neutrophils.        HOCl (250 μM) inhibits hydrogen peroxide production in a dose-dependent manner. Taurine (500 μM) or nitrite (250 μM) neutralizes this inhibition. TauCl has no effect on this production.        HOCl and TauCl induce a chemiluminescence dose-dependent decrease, TauCl (IC50=550 μM) is less efficient than HOCl (IC50=100 μM).        
TauCl and taurine inhibit superoxide anion (O2−) production by stimulated neutrophils. This inhibition involves a different mechanism than those implicated in TauCl formation (i.e., association of the taurine (or TauCl) with a myeloperoxydase specific inhibitor generates a synergic effect).
However, high concentrations of taurine alter LCL. This activity is less important than TauCl (Marcinkiewicz J et al., 1998).
On Polymorphonuclear Eosinophils.
HOCl inactivates sulfidopeptide LTC4 sulfoxides and 6-trans-LTB4 leukotrienes only in an extracellular environment (Owen W F et al., 1987).
On Rat Glioma Cells C6.
In the central nervous system of activated glioma cells, TauCl inhibits production of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) both in dose-dependent and post-transcriptional manners (Liu Y et al., 1999). In addition, TauCl inhibits both the iNOS gene transcriptional expression (i.e., nitric oxide production) and the COX2 expression (i.e., PGE2 production) via a post-transcriptional mechanism (Liu Y et al., 1998).
On Fibroblasts.
In rheumatoid arthritis patients, TauCl inhibits fibroblast-like synoviocyte proliferation and decreases the activity of major transcriptional factors of both IL-6 (IC50˜225 μM) and IL-8 (IC50˜450 μM) in a dose-dependent manner. Thus, TauCl reduces both IL-6 proinflammatory action and immune cell ability to migrate within an inflammatory site (via an IL-8 inhibition). Whereas IL-6 inhibition is independent of the fibroblast stimulating agent used (e.g. TNF-α, IL-1β or IL-17), IL-8 inhibition is dependent on the stimulation via TNF-α or IL-1β, but not via IL-17. This shows different signaling pathways from TNF-α/IL-1β and IL-17 triggered-transduction (Kontny E et al., 1999). These signaling pathways are dependent on two transcription factors: NF-κB and AP-1. In addition, TauCl inhibits both spontaneous and bFGF-stimulated synoviocyte proliferation (Kontny E et al., 2000).
Low levels of both HOCl and physiological chloramines (NH2Cl, TauCl and N-chlorinated α-amino acid) inhibit both DNA synthesis and cell division of cultured human skin fibroblasts (Vile G L et al., 2000).
On Transcription Factors NF-κB and AP-1.
NF-κB-dependent gene expression may be altered by TauCl activity. In IL-1β-stimulated human synoviocytes, transduction TauCl-inhibition of IL-6 and IL-8 is executed via a DNA-bonding ability reduction of NF-κB and AP-1. IL-6 transcription is under a NF-κB control, while both NF-κB and AP-1 control IL-8 transcription. Thus, a (TauCl)=250 μM selectively reduces the DNA-bonding of NF-κB (i.e., the IL-6 transcription) without altering AP-1 DNA-bonding (i.e., the IL-8 transcription). TauCl acts on both NF-κB and AP-1 transcription factors to inhibit the IL-6 and IL-8 transduction. At 500 μM, TauCl decreases the DNA-bonding activity of both NF-κB and AP-1 (i.e., the transcription of IL-6 and IL-8 is reduced) (Kontny E et al., 2000). These two transcription factors are regulated via a redox mechanism ((Sen C. K., Packer L., Fased J. 1996; 10:709-20), (Li N. & Karin M., Fased J. 1999; 13:1137-43), (Kunsch C. & Medford R. M., Circ Res. 1999 Oct. 15; 85(8):753-66)). It seems that TauCl may interfere the intracellular redox status of these transcription factors and, therefore, some anti-inflammatory properties may be suggested from TauCl (Kontny E et al., 2000). On complement.
The C5 component of the human complement may be activated by oxidants, e.g., hydroxyl radicals, hypochlorite or chloramines (i.e., TauCl and mainly NH2Cl). This activation is due to a C5 structural change induced by a Met. residue oxidation within the C5 protein without peptide cleavage. These changes lead to a C6 bonding site expression, which normally is formed after a C5 specific cleavage in C5a and C5b, via one of two C3/C5 convertases. The C5-oxidation product is similar to C5B. Thus, it is able to initiate the combination of the C5-9 membrano-lytic complex.
Chemotactic fragments are not directly generated, but activated C5 components (like C5b) are readily attacked by enzymes such as kallikrein, which produce C5a-like fragments that have a chemotactic activity. It is likely that the C567 complex generated with C5 also have a chemotactic activity (i.e., similarly to C5b67 complex). In addition, the C5b-9 complex is known to stimulate PMNs at non-toxic concentrations. Thus, the same property may be suggested for the corresponding C5-9 complex and, consequently, this may lead to a vicious circle that increases tissue lesions (Vogt W, 1996).